Don't Forget

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DON'T FORGET: "Comet 17P/Holmes is still big and beautiful," reports Chris Schur (comets133@yahoo.com) of Payson, Arizona. "Here is the latest deep exposure from last night."
http://spaceweather.com/comets/holmes/28dec07/Chris-Schur1_strip2.jpg (http://spaceweather.com/comets/holmes/28dec07/Chris-Schur1.jpg?PHPSESSID=8mpjp8hvkfdta46332vus10if2)
"The comet is easy to see with the naked eye from dark-sky sites and is growing more gigantic every day," he says. Indeed, the main problem with telescopic observations is fitting the oversized comet in the eyepiece. Binoculars (http://www.spaceweather.com/xtra/results_canon.php?searchTerm=astronomy%20binocular s) and small telescopes (http://spaceweather.com/ccount.php?linkURL=http://meade.com) work best. Look north after sunset: sky map (http://spaceweather.com/images2007/28dec07/skymap_north_tuttle.gif?PHPSESSID=8mpjp8hvkfdta463 32vus10if2).

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APPROACHING COMET: Comet 8P/Tuttle is approaching Earth for a 25 million mile close encounter on New Year's Day. Until now, the comet has been a target for telescopes only, but "tonight I was able to see Comet 8P/Tuttle with the naked eye and averted vision," reports Doug Zubenel (nzubenel@kc.rr.com) in rural Pottawatomie County, Kansas. A 2-minute exposure with his Canon Rebel XTi (http://www.spaceweather.com/xtra/results_canon.php?searchTerm=Canon%20Rebel%20XTi) revealed Tuttle's lovely emerald color, shown above:
http://spaceweather.com/comets/tuttle/26dec07/Doug-Zubenel1_strip.jpg (http://spaceweather.com/comets/tuttle/26dec07/Doug-Zubenel1.jpg?PHPSESSID=ri180ki6ljip3n4uomsgai6580)
The green hue is a sign of cyanogen (CN, a poisonous gas) and diatomic carbon (C2) in the comet's atmosphere; both substances glow green when exposed to sunlight in the near-vacuum of space. This green color could intensify in the week ahead as the comet nears and brightens to a predicted magnitude of 5.7. It's easy to photograph. Just point (http://spaceweather.com/images2007/27dec07/skymap_north_tuttle.gif?PHPSESSID=ri180ki6ljip3n4u omsgai6580), click (http://www.spaceweather.com/xtra/results_canon.php?searchTerm=350D%20digital%20rebe l), and submit your image (http://spaceweather.com/submissions/index.php?PHPSESSID=ri180ki6ljip3n4uomsgai6580).